As known for instance from U.S. Pat. No. 6,261,097, which has been assigned to the present assignee, dental implants may be stored prior to their use in a sealed ampule which is preferably filled with a storage fluid.
During storage the dental implant is temporarily coupled to a holding element which holding element is used in the course of storage to retain the dental implant firmly in position within the ampule. Later, when the dental implant is removed from the ampule for implantation into a respective bone, the holding element is gripped by the user to be placed into the implant site. The holding element is furthermore adapted for temporary positive attachment to manipulating tools that facilitate the removal of the dental implant from the ampule and the placement thereof into the bone at the implant site. Ultimately, when the dental implant is implanted at the desired site in the bone, the holding element may be removed from the dental implant. Nevertheless, as the holding element is screwed to the dental implant, the overall handling is tedious.
From WO-A1-2005/037126, which has also been assigned to the present assignee and the content of which is herewith incorporated by reference, there is known a holding element wherein the use of a screw for the coupling thereof to the dental implant is avoided.
As shown in FIGS. 1 through 3, that illustrate the prior art known from WO-A1-2005/037126, the known holding element which is generally designated by reference numeral 1 includes an engagement section 2 adapted for positive engagement with a manipulating tool not shown. The engagement section 2 is embodied as a polygonally shaped end, for instance as an octagonally shaped end. Adjacent to the engagement section 2 there is provided a radial groove 3 for accommodating an O-ring 3A shown in FIG. 2 that has a securing function to the manipulating tool not shown.
Furthermore, as indicated with particular reference to FIGS. 1 and 1A, the holding element 1 has a retention section 4 with two adjoining annular shoulders 5 and 7 and an intermediate cylindrical section 6 of a reduced diameter adapted for retention in an inner ampule indicated at 20. The retention section 4 is joined to the engagement section 2 by a breaking point member 30.
The known holding element 1 further includes, adjacent to the retention section 4, a clamping section 8 with a first radial groove 9, a force transmission element 10 with an octagonal shape for the positive engagement with a dental implant 14, a second radial groove 11 and a tapered member 12. As shown in FIG. 3, the second radial groove 11 is provided with a clamping or lock ring 13 made of PEEK (poly ether ether ketone) including a peripheral clearance 13A for facilitating the mounting thereof.
The dental implant 14, in turn, is provided with a cavity 15 having an inner surface 17 that matches the surface of the force transmission element 10, such as to provide for a positive engagement between the dental implant 14 and the holding element 1, whereby the dental implant 14 is rotationally secured to the holding element 1. The cavity 15 of the dental implant 14 further includes an undercut 18 sized for clampingly receiving the lock ring 13 and a conical terminal section 19 closely enclosing the first radial grove 9 of the clamping section 8 of the holding element 1.
While providing for a better handling and facilitating the separation of the dental implant from the holding element it has been nevertheless noted in the practical implementation that the known solution of WO-A 1-2005/037126 still suffers some drawbacks, inasmuch the clamping force of the prior art PEEK lock ring 13 changes in time or is variable ad initio, and therefore it is difficult to precisely adjust the clamping force when the implantation is carried out. This problem is of particular concern if the dental implant is stored over a longer time span and is even further aggravated if the storage medium is a fluid.
In addition, the prior art lock ring tends to release carbon that may in turn damage the surface of a dental implant, particularly an SLA treated dental implant surface.
Furthermore, the manufacturing tolerances of the prior PEEK lock ring are very strict, and therefore the production thereof may become cumbersome.